<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<link rel="stylesheet" href="css/bootstrap.min.css">
	<title>Document</title>
	<script src="js/jquery-3.1.1.min.js"></script>
	<script src="js/bootstrap.min.js"></script>
</head>
<body>
	<div class="container">
		<div class="btn-group">
			<button class="btn btn-danger dropdown" data-toggle="dropdown">
				按钮下拉菜单
				<span class="caret"></span>
			</button>
			<ul class="dropdown-menu" role="menu">
				<li><a href="">1</a></li>
				<li><a href="">2</a></li>
				<li><a href="">3</a></li>
				<li><a href="">4</a></li>
			</ul>
		</div>
	</div>
</body>
</html>